Immunizations – catch-ups and boosters

Any immunization given after the recommended age is called a “catch-up” immunization. Catch-up immunizations aim to provide the best possible protection against disease as quickly as possible by completing the recommended, age-appropriate vaccinations.

People can miss scheduled immunizations for many reasons and may need to start a catch-up program. People who have recently arrived from another country may also have missed immunizations that are routinely given locally.

When the immunization history is uncertain#

If a doctor is unsure whether you have been immunized because there are no written records, the general rule is to go ahead and have the vaccine. For most vaccines there are no serious adverse events linked to extra doses if you are already immune.

The immunizations you may need depend on your health, age, lifestyle and occupation. Together these factors are sometimes referred to as HALO. Talk to your doctor or immunization provider if you think you, or someone in your care, has health, age, lifestyle or occupation factors that could mean an immunization is needed.

Ideally, a catch-up plan should be based on written records showing which immunizations you have had. However, records are not always available, especially for people who have moved, been separated from their families or newly arrived from another country. If there is doubt about your immunization status, it can help to:

• Try to locate any immunization records your family may have kept, such as a personal child health record.
• Contact any doctor, clinic or local authority that may have given you vaccines in the past, including school-based vaccinations, to see if they still hold records.
• Consider your age as a guide — for example, you may have been older than the recommended age when a particular vaccine first became available.

A blood test can sometimes check immunity against certain diseases. A doctor may also look for scars from past vaccination; for example, the BCG vaccine leaves an identifiable mark on the skin in most people who receive it.

How a catch-up schedule works#

A catch-up schedule may differ from a standard routine schedule, depending on your HALO and immunization history. For example:

• The interval between doses may be shortened.
• If more than one vaccine has been missed, catch-up doses may be given at the same time in different arms or legs. This does not overload the immune system and ensures protection is provided as early as possible.
• An older child may receive a different formulation than the one normally given at the recommended age. For example, a child aged 10 years and over may receive the adult and adolescent form of the diphtheria, tetanus and whooping cough (pertussis) vaccine as a booster.
• Some doses or vaccines can be skipped when they are no longer needed at a given age.

Adults and children with medical risk factors may need extra doses incorporated into their catch-up schedule. If you are concerned that your catch-up schedule differs from the standard recommended schedule, ask your doctor or immunization provider for more information.

Catch-up for people who have recently arrived#

Each country has its own vaccination schedule, which may differ from the local one, and some infectious diseases that are common in one place may be rare or absent in another. People who move to a new country may need catch-up vaccinations to be considered up to date.

Some things to keep in mind are that certain vaccines available in one country may not have been available in another, and immunity to some diseases can be confirmed by a blood test. A newly arrived person’s catch-up schedule may differ from the routine program depending on their age and which vaccines have been missed. Information in languages other than the local one is often available to help.

Where to get immunized#

Doctors, some pharmacies and local health clinics can immunize you and your family, and local authorities may also run immunization sessions. Many vaccines are provided free of charge or at reduced cost to specific groups; your provider can advise you of any service fee or costs involved.

Before being immunized#

To reduce the risk of unwanted side effects and to make sure the correct vaccine and dose are given, tell your doctor or nurse if you, or the person about to be immunized:

• Is unwell, or has a disease or treatment that lowers immunity (for example leukemia, cancer, HIV, radiotherapy, chemotherapy, oral steroid medicines such as cortisone and prednisone, or disease-modifying anti-rheumatic drugs).
• Has had a severe reaction following any vaccine, or has any severe allergies.
• Has had any vaccine in the past month, or an injection of immunoglobulin, blood products or a transfusion in the past year.
• Is pregnant, planning a pregnancy, or is a parent, grandparent or carer of a young infant.
• Has a history of Guillain-Barré syndrome, was born preterm, has a chronic illness, a bleeding disorder, or does not have a functioning spleen.
• Lives with someone whose immunity is lowered by illness or treatment.
• Is planning travel, or has an occupation or lifestyle factor for which vaccination may be needed.

Side effects after immunization#

Immunizations are effective and safe, although, like all medicines, they can have unwanted side effects. In virtually all cases, side effects are far less serious than the symptoms of the disease itself. Common side effects are usually mild and temporary, occurring within a day or two of vaccination, and specific treatment is not usually required.

Side effects can include a mild fever and pain at the injection site. To manage these:

• Drink extra fluids and avoid overdressing if there is a fever. Although routine use of paracetamol after vaccination is not recommended, if fever is present, paracetamol can be taken — check the label for the correct dose or ask your pharmacist, especially when giving it to children.
• A cold compress on the injection site, and paracetamol if needed, can ease soreness, redness, itching, swelling or burning, which may last a day or two.

There is a very small risk of a serious allergic reaction (anaphylaxis). This is why you are advised to stay at the clinic for at least 15 minutes after immunization, in case further treatment is required.

If a side effect is unexpected, persistent or severe, or if you are worried about yourself or your child after a vaccination, see your doctor or immunization nurse as soon as possible, or go directly to a hospital. Your immunization provider can tell you how to report an adverse event. It is also important to seek medical advice if you or your child are unwell, as this may be due to another illness rather than the vaccination.

Extra doses#

If there is no way to be sure whether you have been immunized, a catch-up immunization is generally recommended, which sometimes means a person receives an extra dose they did not need. For many vaccines there is no increased risk of side effects from an extra dose. For some, extra doses may slightly increase the risk of mild reactions such as soreness, redness and swelling at the injection site. Discuss these risks with your doctor.

Protection takes time and may not last forever#

Some vaccines take time to provide protection and may not give lifelong immunity. This is why, in most cases, a course of injections is given over time to build up immunity, and why booster shots are sometimes needed.

For example, immunity to all three types of poliovirus can take two to three months to develop after immunization. This may matter if you plan to travel to a country where polio is common. Booster shots of the polio vaccine are recommended every 10 years for adults who travel to places where polio is common, or who work with people who have contracted the disease. Speak to your doctor or immunization provider if you have any concerns.

Key points#

• Vaccines often require more than one injection to offer protection, so it is important to receive all recommended doses and booster shots.
• Adults and children with medical risk factors may need extra doses incorporated into their catch-up schedule.
• Common side effects following immunization are usually mild and temporary, occurring within a day or two, and specific treatment is not usually required.
• An extra vaccine dose may slightly increase the risk of mild side effects for some vaccines, so discuss these risks with your doctor.

Where to get help#